Probably they started from some group or groups of
the Amphibia in the later Carboniferous, when, as we saw, the
land began to rise considerably. We have not yet recovered, and
may never recover, the region where the early forms lived, and
therefore cannot trace the development in detail. The fossil
archives, we cannot repeat too often, are not a continuous, but a
fragmentary, record of the story of life. The task of the
evolutionist may be compared to the work of tracing the footsteps
of a straying animal across the country. Here and there its
traces will be amply registered on patches of softer ground, but
for the most part they will be entirely lost on the firmer
ground. So it is with the fossil record of life. Only in certain
special conditions are the passing forms buried and preserved. In
this case we can say only that the Permian reptiles fall into two
great groups, and that one of these shows affinities to the small
salamander-like Amphibia of the Coal-forest (the Microsaurs),
while the other has affinities to the Labyrinthodonts.
A closer examination of these early reptiles may be postponed
until we come to speak of the "age of reptiles.
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